ABC News says Dzhokhar Tsarnaev told interrogators the brothers scrapped the plan when they learned to build functioning explosives much sooner than expected.

Federal court documents say as early as March, the younger Tsarnaev told close friends that he knew how to make a bomb.

NewsCenter 5 also confirmed that federal authorities believe the pressure cooker explosives used to maim and kill on Boylston Street were constructed at Tamerlan Tsarnaev's Cambridge apartment.

Investigators may also learn more from Tameralan Tsarnaev's wife who received a phone call from her husband days after the attack.

The explosions killed three people and injured more than 260 others.

Agents say three of the Dzhokhar Tsarnaev's friends removed a backpack containing bomb making components and a laptop from the captured suspect's UMass Dartmouth dorm room.

The emptied fireworks and backpack were recovered from a landfill.

Sources tell NewsCenter 5 that agents recovered the laptop as well, ossibly a critical piece of evidence. It was given to them by one of Dzhokhar Tsarnaev's friends.

Look back: Jennifer Hudson dazzles Esplanade crowds

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Neil Ungerleider/WCVB-TV

Jennifer Hudson

Academy Award-winning actress and Grammy Award- winning recording artist, Jennifer Hudson was the star of the 2012 Boston Pops annual July 4th concert on the Esplanade. She is seen here during the July 3rd rehearsal concert.

INVESTIGATION. THE "EYEOPENER"'S JOHN ATWATER HAS BEEN TRACKING THE OVERNIGHT DEVELOPMENTS AND JOINS US LIVE FROM BOSTON IN A VERY PLACE THEY WERE LOOKING AT. NEWSCENTER 5 HAS CONFIRMED THAT THESE BROTHERS ALLEGEDLY HAD THEIR SIGHTS SET ON THE ESPLANADE ON THE FOURTH OF JULY. AND POTENTIALLY SOME OTHER TARGETS IN BOSTON AND IN CAMBRIDGE. BEFORE THEY WERE CAPTURED ON SURVEILLANCE TAPE HERE AT THE MARATHON THE SUSPECTS ALLEGEDLY DROVE AROUND BOSTON AND CAMBRIDGE CHECKING OUT POLICE STATIONS, THE GLOBE REPORTING THAT THEY WERE HATCHING A PLAN TO LAUNCH AN ATTACK ON LAW ENFORCEMENT OFFICERS. WHICH COULD OF COURSE SHED NEW LIGHT ON THE SEEMINGLY RANDOM KILLING OF M.I.T. POLICE OFFICER SEAN COLLIER. THIS REVELATION COMES AFTER NEWSCENTER 5 CONFIRMED THAT TAMERLAN AND DZHOKHAR TSARNAEV ALLEGEDLY FIRST WANTED TO ATTACK THE FOURTH OF JULY ON BOSTON'S ESPLANADE, BUT CHANGED COURSE WHEN THE BOMBS WERE BUILT FASTER THAN ANTICIPATED. WE'RE ALSO GETTING NEW INFORMATION ON TAMERLAN TSARNAEV'S WIDOW. INVESTIGATORS SAY THAT SHE GOT A PHONE CALL FROM HER HUSBAND DAYS AFTER THE ATTACK, AND THE "NEW YORK TIMES" REPORTS THAT SHE STOPPED COOPERATING WITH INVESTIGATORS. SHE HAS INSISTED OF COURSE THAT SHE KNEW NOTHING ABOUT THE ALLEGED BOMB PLOT. INVESTIGATORS SAY THERE IS ANOTHER CONNECTION TO THE ESPLANADE HERE THAT THE YOUNGER BROTHER HAD COME DOWN HERE IN THE PAST WITH SOME FRIENDS, TO LIGHT OFF FIREWORKS ALONG THE

Lawyers for the Boston Marathon bomber prepared to rest their case Tuesday after an FBI fingerprint examiner testified that Dzhokhar Tsarnaev's fingerprints weren't found on any of the marathon bomb components, but his older brother's were.